Abstract There is an urgent need to establish Quality target product profile (QTPP) for topical products and identify the Critical Quality Attributes (CQAs) to develop meaningful drug product specifications based on clinical performance and to ensure equivalent safety and efficacy to the Reference Listed Drug (RLD).Most semisolid preparations such as pharmaceutical/ cosmetic creams, ointments, lotions etc. display complex flow behaviour including breakdown on application of high shear, thixotropy and viscoelasticity which can be described by the methods used in measurement of these parameters. Most of the semisolid systems such as ointments, creams, pastes, and gels are viscoelastic in nature as they display both liquid and solid properties within the same material. In this project we aim to vary key formulation and manufacturing parameters to identify and define potential failure mode that effect a products performance. We will compare bioavailability using both finite (in use) and infinite dosing and use tools such as Atomic Force Microscopy (AFM), Confocal Raman and multiphoton microscopy to study the effects of excipients and formulation on in vitro and in vivo skin. Apart from BE we aim to define cosmetic equivalence (CE). Sensorial similarity/cosmetic equivalence will be defined as a critical quality attribute through this process.